Production of aromatic bodies



April 2, 1946- c. wElzMANN 2,397,715

PRODUCTION OF AROMATIC BODIES Filed Jan. 9, 1942 2 Sheets-Sheet 1 fig.2.

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April 2, 1945- c. WEIZMANN 2,397,715

PRODUCTION OF AROMATIC BODIES Filed Jan. 9, 1942 2 Sheets-Sheet 2Patented Apr. 2, 1946 Charles Weizmann, London W. C. l, EnglandApplication January 9, 1942, Serial No. 426,243 In Great Britain April23, 1941 (Cl. 26o- 668) 2 Claims.

This invention relates to aromatic bodies, namely, the production ofaromatic hydrocarbons.

I have found that mineraloils, especially of relatively high-boilingrange, are converted into aromatic hydrocarbons, to a considerableextent such of comparatively low-boiling point, such as benzene,toluene, xylenes and ethylbenzene. 'I'he process consists in passing thevaporised mineral oil over a metallic catalyst belonging to the group ofmetals catalysing hydrogenation and dehydrogenation reactions.Together'with gaseous products, such as hydrogen, methane, ethane,propane, butane and the corresponding oleilns,l a liquid is formed,which, apart from a very small amount of low-boiling (below 80 C.)highly unsaturated material, consists of aromatic hydrocarbons. It isassumed that the hydrocarbon molecules break down to very small units,such as olens, dienes and acetylenes. products are then diorpolymerised. cyclised, if necessary, and dehydrogenated. All theseprocesses appear to be catalysed by the same, abovementioned catalyst.

The process is a true cracking process, as its distinct feature is theproduction of substances chiefly of lower molecular size, compared withthe starting material. As with other cracking proeesses, a certain partof the product has a boiling range higher than that of theinitialmaterial.

Further I have found that a low-boiling bituminous shale oil (S-180 C.),and a low-boiling, low-temperature coal oil (o-180 C.), may be convertedinto aromatic hydrocarbons. It has now been discovered according to thisinvention that such conversion is not limited to oils such as shale oiland coal oil but that low-boiling The cracking petroleum fractions ingeneral, natural or synthetic, provide good starting material for theprocess of aromatisation.

The product substantially consists of pure and easily separable aromatichydrocarbons, notably benzene. toluene and a product, boiling at l36145C., being pure ethylbenzene or a mixture thereof with small quantitiesof xylenes and styrene, depending on the nature of the starting materialprocessed. With a straight-run gasoline of boiling range 10o-180 C., e.8. under certain well-defined conditions, as much as 7% benzene, 14%toluene and 14% xylenes. containing ethylbenzene and styrene have beenisolated, together with a minor quantity of higher alkylbenzenes,boiling between 140 and 180 C. (6%) and a heavy oil (5%), all thepercentage figures being calculated on the feeding-stock. As the productobtained has a boiling range similar to that of the raw materialprocessed, the new process may be described as "catalytic, aromatisingreforming; it must. however, be remembered that part of the material isrecovered as a high-boiling mixture of aromatic hydrocarbons, containingnaphthaiene, anthracene andl other polycyclic compounds.

Part of the material is converted into gaseous products. The gasescontain hydrogen, methane, ethane and ethylene, propane and propylene,butanes and butenes andthe like and are therefore useful for furthertransformations, at least the msaturated constituents, propane and thebutanes. The remainder may be used as fuel or for other purposes. AAfurther by-prcduct, obtained in comparatively very small amount,'is avery low-boiling liquid (2S-80) which contains olee fines, dienes andthe like and may be utilised accordingly. It is evident, therefore, thatthe liquid product obtained in my process, aside from a small,low-boiling, highly-unsaturated product, consists substantially ofaromatics covering the entire range from benzene to polycyclic`compounds.

The process may be carried out in general terms as follows:

The vaporised feeding-stock or a mixture of the vapours with inert gasespasses at a temperature ranging between 600 and 750, but preferably inthe neighbourhood of 650 C. and at a pressure substantially nearatmospheric pressure. over a. catalyst, consisting of a metal chosenfrom the group given below, or a mixture or alloy of v a plurality ofsuch metals, either in compact form or deposited on a carrier, such asasbestos, pumice, bentonite and the like, which in itself has nocatalytic effect on the hydrocarbon vapours under the specifiedconditions. The catalyst is placed in a horizontal or vertical steeltube, the material of which may or may not effect the same conversion asthe catalyst, which will always have the predominant influence on thevapours, due to its much larger. active surface. The catalyst metals arechosen from the grouprof hydrogenation and dehydrogenation catalysts.thatfi'sfto and the permanent gases are collected and uti-l lised asdesired. The products dissolved in the scrubbing liquid are removed byheating and together with the first liquid product subjected to acareful fractionation. It is also possible to isolate the reactionproducts by a process of fractional condensatlon. The aromatic products,so

isolated with great ease, are substantially pure crackingdescribedabove."

A'rnc catalyst does not became'- appreciably 111-.

- xlictivated by carbonisation, which occurs in'similar-processes. knowninthe conversion o t hydrocarbon .-oils.- If. however. a, markeddecrease in activity has-taken place, thereactivation can .be

enectedlby successive treatment Awith oxygenor f oxygen containinggasesand hydrogen-or-'hydrofgen'containing gasesat appropriate temperaytures.. For -the second step in thurs-activation.

the gases may-conveniently be'.used ylrhichfre-'-v main after removal ofthe otherwisev -useiul constituents zirom the gaseous products;obtainedby theprocess oi catalytic, aromatising reforming The easewith'whichthe low-boilingl lviydrocurfV bon oils are aromatised.1li-ascribed -to thecooperation vo'i two mechanisms:l (1) That describedabove, linvolving but'ylene, butadiene, acetylene, their -dlor poly'merisation, cyclo-isomerisation', or dehytirogena-v tive cyclisation ofthe polymerisation products, it they are not already hydroaromatic,and-{dehydrogenative aromatisation. -It is signincantf that the amountof oleilnes in the cracking gases4 destruc l tionof the molecules intolow-moleculen` unsaturated compounds, such as ethylene, propylene,v

' il?? VIls Producti@ salumi-ange) ory the feedlngmk. atleast as oflow-boilingaromaticsis u concerned.

. yI'hecc"considerations make it clear thatnot all .'thehydrocarbonspresent in-a gasoline are arowith equal ease. Substances likev meth- Iyl-pentane or ethylbutane. inI general with. less six'carbon' atoms in astraight chain, can V;

`be aromatised by the nrst mechanism, and structuraliniluences willalways play a part in y.th e speed{a1'1d ease oi aromatisation. a

*The invention consists ina process for the .Y conversion of aliphaticand `hiidroc'romatic min- .eral oilbodiesas herein set` out into aproduct 'comprisinga liquid-mixture of aromatic mbstances by subjectingastarting material as herein set forth to treatment by heat within 3 thetemperature range of 60G-750. C. for the production'oi a mixture ofsubstantially-pure aromaticv hydrocarbons, in contact with ahydrovgenatiou` and dehydrogenation catalyst.

' The invention also consists in processes for;v

fthe. conversion of'valiphatic land' hydroaromatic l .mineral-oilbodies-as herein set out into a procluct comprising a liquid mixture oi'aromatic subfollow. particulars of an example appliedv to the" femployment.. of* one of the. feeding-stocks men-` vstancessubstantiallyfree from vsulphur and .ni-

tragen compounds VVsubstantially as. herein de-` I .will nowgiveparticulars relating.. t0 the a ieedin'g-stock which have been employedin-certain examples ot `the present invention. Then tione'd, followedbya'nother sp'eclc example and then by tabulated references toothe'rfexamples more. details orwhichare shown in graphs as Eindicatedlater.

I nannte-Sr@ ron Anouxsrrsms samplesfoffrexss crude 21 n.11. I. 11cm:aisv10v l tillatesand their .extractaprepared'with'lOO/ is lower'whenthe speed ofl throughput isrelaf tively lowindicating that these olennesare- -fliquid sulphur dioxide,

used"v had` 'the following aromatics of substantially the same numberofl carbon'atoms. It can Well be imagined that' some of the productsformed due tothe iirst mechanism by di-` and polymerisation vof thesimple oleiines, are already present in the feeding stock. Thismechanism becomes; obviously suppressed with the increasing molecular'vweight boiling gasolines 'can most easily be explained aromatised to ahigher proportionand the characteristics:

Y sampled Sam lc B Sample C 'Sample D (gasoline (gasoline (extract 1 a0c.) 10o-180 c 15o-wc.) 15o-250 0.)'

. 0.100 l 0.101 i 0.839; 0.855 v 4s 4a 50.15 -cao 9s c4 1oz 14a 111 104.110 15s n 114 110.5 111. 5 115 n 111.5 18a 182 l n 125 188 n 132 1315192.5 193v n 13s. 1 40 .20o 200. m 14s 149 v1:01' 201 m 154 151 210 215n I, 167 227.5 226 9 q2 m 111 11s 239 236 F. B. P 10c 191 250 252Bromine consumption min/g 8 111 8v 81 Solubility in dimethyl sulphate--percent.--.` 18 18 l 10l 20 formation of 1ow. boiling aromatics fromhigher GMPHS YReferring to the five accompanying graphs,

.l Graphs Ito IV have reference to gasoline and namely, in Graphs I andII,the chain curves c *applyto further cracked products.

Graph' V has 'reference' to heptane. `All the graphs show therelationship between temperal ture in degrees .centigradeand percentage:of dis- Ia is for the gasoline of boilingrange of 100- C.. sample AJabove. Ila is for the gasoline extract of boiling range of 100-180' C.,sample B above. IIIa is for the gasoline of boiling range of o-250 C.,sample C above, and IVa is for the gasoline extract of boiling range of150-250 C., sample D above.

The dash curves b are all for products obtained by cracking' at 650 C.The chain curves c are both for products obtained by cracking at 680 C.

In Graph V, the vertical full-line d applies to heptane and thedash-line e applies to the product cracked at 580 C.

EXAMPLE 1.-ARomArIs1NG Rxrolulmc or Sutri.: A

The catalyst consisting of a mixture of ne copper and iron turnings inthe ratio of 5:1 and placed in a steel tube of 1 metre useful length and'7.5 cm. diameter, was activated, by successive oxidation with air at400 C. and reduction with hydrogen at 250 C. and was then brought to atemperature of 650 C. Into the catalytic furnace, 1 kg. of the gasolinesample A was introduced at a rate of 126 g. per hour. The vapours of thereaction product were cooled with an eilicient water-jacketed condenser,giving 452.5 g. liquid product, and were then passed through a tower,ruled with 45o ce. spindie ou, which absorbed 83.5 g. liquid products.`'I'hese were rewere shown to be entirely aromatic by the usual methods.The effect of the process is demonstrated by Graphs Ia and Ib, whichcontain the boiling curves of the initial and the ilnal product.

Itk is possible to increase the amount of lowboiling aromatics, and ofthe very high-boiling aromatics. by re-cycling the fraction boiling at14S-180 C. over the same catalyst.

The fraction 145180 was subjected to fractionation and was shown tocontain the following principal constituents:

Bolling point, degrees Isopropyl-benzene 151 1.3.5-trimethyl-benzene(mesitylene)-- 162 Tert. butyl-benzene 168 1.2.4-trimethyl-benzene 170Sec. butyl-benzene 174 1.2.3-trimethyl-benzene 179 Indene 181 Percent otSubstancel Boiling range total high Remarks fraction Tetrahydronaphthalene. m5210 C 5. 0 N aphthalene 210225 1l. 3a-Methyl-naphthalenc- 240-247 4. 2 Picrate M. P. 140.a-Ethyl-naphthalene--. 252258 5.0 Picrate M. P. 116. Unidentiiied265275- 4. 2 Picrate M. P. 122-123". l

o 195 in vacuo... 2. l Orange red picrate M. P. 134.

Anthracene 24W-210 in vacuo.. .s l2. 0 Unidentified substance.-. 345-347in vacuc.. .i 7. 3 Dark-red Picrate M. P. 19o-108. Unidentifiedhydrocarbon. 350410 in vacuo... i 1.0 M. I. 288 Pitch Above 410 invacuag 25 covered by heating the scrubbing liquidvto 200 C. and werecombined with the first liquid.

The non-condensable gases amounted to 408 litres with a speciilc densityof 1.149 g. per litre,

i. e. to 469.2 g. A sample of gas was taken before the scrubbing towerand showed the following composition:

Total amount Percent (by Percent (by formed "om volume) weight) l kggasoline Grams Hydrogen 13. 90 l. l0 l5. 2 Meth 37. 85 23. 50 110. 2Ethane 9. 1l. 30 53. 0 Ethylene 15. 40 16.75 78. 8 Propane l. 3. 15 14.8 Propylene 10. 30 16. 80 78. 8 Butanes 0. 45 1. 00 4. 7 Butylenes (aand 3. 55 7. 70 38. 4 Iso-butylene 2. 6. 30 29. 5 Pentanes and pentenes.2.05 5. 67 26. 6 Hexanes and hexenes. 2. 05 6. 75 3l. 0

The liquid reaction product was subjected to a careful fractionation,and the followin cuts were` g 6# creased; the constituents containing intheir Heavy aromatics (boilingd above C.) 58.5

Tolerance :2%.

All the products. apart from the lowest one, 16 Ethyl-benzene fraction.

Substantial quantities of anthracene and especially chrysene may beisolated from the pitch.

The above list contains only the substances which have been isolated insubstantial quantities; it does not indicate that thetabulated compoundsare the only products formed.

According to a modification the charging stock was passed over acatalyst consisting of activated 0 copper at a temperature of 600 C.'I'he total catalyst volume was 640 cc. of which 440 cc. were at theindicated temperature, while the temperature decreased by about 15towards the ends of the furnace. As the rate of throughput was "I0 cc.per hour, the space veioclty was 0.16 litre per litre catalyst space perhour. 96% liquid product were recovered, while 4% of the charging stockwere converted into gaseous products. 'I'he composition of the liquidproduct was, however, different from that of the starting material: 15%boiled up to a temperature of 145 C., 10% above so that '15% hadretained the original boiling range. Fractionation of this part showedthat the relative amount of trimethyl-benzenes had in- Per cent Belowbenzene 1.3 Benzene 1.5 Toluene 1.5 12.0

v 55% are mesitylene.

Similar experiment was carried out at 68o C.

190.v Fractionation of the low traction showed that it consisted of Percent Head lfractionv 0.7 Benzene 3.5

Toluene 8.0

\ Ethyl-benzene 16.5 t

'I'he total amount ot low boiling aromatics is therefore higher than atson' c. and the increase in toluene is especially marked. In both cases,

however, the ethyl-benzeneiraction is the principal constituent.

In the fraction boiling between 'ur-190 c; From the highest tractionnaphthalene and temperature of 580 C. and at a rate of 200 s. per hour.I'he reaction product consisted of 732 g. liquid and 250 litres=225 g.gas. 'I'he product was not completely aromatised, although a fraction oiessentially pure benzene and toluene could be isolated, onfractionation. The incomplete aromatisation was indicated by theobservav tion that only of the liquid were soluble in dimethyl sulphate,which does not dissolve n-heptane at all. It'was further observed thatthe liquid reaction product had a bromine consumpv tion oi' 227 mg.grams while the initial n-heptane anthracene were easily isolated; aboutof this fraction consisted of chrysene.

Oran Exmus nr Tissus Foxx The results o! other examples are summarisedin the following table, and the eilect oi processing is demonstrated bythe vaccompanying Graphs Nos. I to IV. All results are calculated on lkilogramme of starting material. Example 'A em`` ploys as a catalystcopper on pumice. Examples B, B1, C and D have copper-iron' catalysts.

' Feeding-stock 1 A B Bl O D 'rem ture --9 C-- cao y eso eso 65o cto Ca(l) v 0) 0) 150 154 143 167 203 488 l 398 1 480 l 356 1 282 1 l(l. 1)(1. 1) (1. l) 1. 18 (l. 1) 537 438 508 4Z) 310 450 544 402l 496 644 12596 v 136 Z 324 Boiling below 80..do-..- 6.8 42.2 12.5 22.1 21.3 Benzene.-do'..-- 145.0 88.4 135.8 74.1 38.2 Toluene do-. 113. 1 151. 2 119. 681. 9 124. 0 X lene fraction-. do.. 42. l 1,26. 3 50. 5 69. 9 80. 8 Rberalkylbenzones -.do-... 18.0 40. 2 37.4 40. 3 46. 9

l Copper on pumice. l Copper-iron. v

.Composition of gas from working sample C at tsar-o. g

Percent by Percent by volume weigh Hydrogen 11.215v 0. 8 Methane 36. 9022. 3 Ethano-- 12. l0 13. 7 Ethylene 15. 95 16. 9 Propane.-. 2.40 3. 9Propylenell. 05 e 17. 5 Butanes. 0. l. 2 Butenes 3. 90 8. 2 Iso-butylene2. 4. 6 Pentanes and pentenes 2. 30 6. l Hennes and hexenes 1.40 4. 5

Examen: ron Inraovnso 'rus Germ Ramto or N-Hsrrm 1 kg. n-heptane (3.1.iis-100) was miseri over the catalyst described in Example l at aPercent by Percent by volume weight 0 0 22. to 11, so' 21.00 20. 0526.00 23. 3. l 4. 50 17.' 45 23. 30 0. 50 0. 90 5. 65 l0. 05Iso-butylene- 1. 55 2. 76 40 Pentanes and peatones 1. 45 3. 25

Gllllul.'

was entirely saturated. The initial n-heptane is converted by theprocess described, into a liquid which has'the octane number 62.

The boiling range of the liquid as approximately shown in Graph V was asfollows;

I. B. P C 40v Up to -per cent-- 3.0 80-85 l do 8.7 -90 -do k- 14.7 -95do 33.1 100 do 28.2 Over.100 (mainly toluene) -do 6.0

The following table summarises the results of the analysis of thescrubbed gas from this example. which gas had a specic gravity of 1.1403g./1itre (at 0 C. and '100 mm. pressure).

In this connection it may be mentioned that the low-boiling aromatichydrocarbons as s uch or their mixtures are useful as constituents ofhigh-grade fuels for internal combustion enveniently utilised forblending purposes, as its blending value has been determined to be 119.

The method gives a possibility to convert low- 1 boiling (10o-250 C.)gasolinas into aromatics.

either into single, well-dencd hydrocarbons or into a mixture ofaromatic compounds with'unchanged or not-wholly varomatlsed(cycloparainnic, olennic') hydrocarbons. a

Variation of the conditions of reforming, both as to temperature andspeed. permits to vary the ratio in whichthe single constituents of thev deriving from this reforming process itself or else lfrom any othersource, or their solvent extracts or ramnates or mixtures.

terials or originating-from synthetic processes such as theFischer-Tropisch process.

In particular, it is possible to use as charging stock directly theproducts of therr'nal` or cata-` lytic cracking of higherboilingpetroleum cuts, without previous condensation or any additionaltreatment. In this case the utilisation of those parts of the reactionproducts, which are gaseous at ordinary temperature and atmosphericpressure, is preferably carried out by using jointly the gases formed inthe cracking and the reforming process, respectively. One can vary thenature of the aromatics formed, at least to a certain extent: highertemperature, e. g.,- gives more benzene at the expense of ethylbenzene.

The compositions of fractionated products given above may have atolerance 22%.

The following is a list summarising suitablev startingmaterials for theprocess according to the present invention, namely:

(a) Products of a cracking or reforming 3 process, carried out bythermal or catalytic methods with the crudes mentioned underv (l), theirmixtures, solvent extracts, or raiilnates.

(b) Gasolines obtained by pclymerisa-A 35 tion processes fromcraekinggases, es-

pecially, those with 3 and/or 4 carbon atoms. their mixtures, solventextracts or ramnates.

(c) Products obtained by hydrogenation 4 oi coal, high-boiling mineraloils, tars. f

creosotes and other carbonaceous materials, thehydrogenaticnbeingcarried out with or without catalyst, in one or morestages.

pounds (3) Synthetic materials: Gasolines, obtained by synthesis fromnon-hydrocarbon materials. especially those originating from thecatalytic reaction between carbon monoxide and hydrogen (Fischer-Tropschprocess).

In connection with gasolines, those most appropriate for treatingaccording to the present,

20 ture Within the range of 600 to 750 C., at substantially atmosphericpressure and at a space velocity ranging from about 0.16 to 0.19` literper liter of catalyst per hour, ,whereby a reaction product is obtainedthe liquid portion -of which 25 consists substantially completely ofaromatic hydrocarbons aside from a small low-boiling, highly unsaturatedfraction, and recovering said aromatic hydrocarbons.

2. In the manufacture of aromatic hydrocarbons from natural gasolineshaving boiling points within the range of about 100 to 250 C., theprocess which comprises passing such a gasoline in vapor form in contactwith a nely-divided metal catalyst capable of catalyzing hydrogenationand dehydrcgenation reactions, at a temperature within the range ofabout 600 tc 750 C., at substantially atmospheric pressure and at aspace velocity ranging from about 0.16 to 0.19 liter per literl ofcatalyst per hour, and condensing the resulting vapors, wherebyaliquidreaction product is obtained which. aside from a small,low-boiling, highly-unsaturated fraction, consists substantially oi'aromatica covering the entire range from benzene to polycyclic com-

